i found the c-speed compression calculator but i cant find what octane gas is required for each compression ratio. so the question is how high can my compression be on pump0 gas?

 

Everyone will tell you it depends on the tune, and it's pretty much true. You can't say XX compression needs YY octane, that's not what that calculator is for. It's up to you to excersize common sense in selecting a compression ratio.

I have seen several cars at close to or exceeding 13:1 compression running 93 octane. 12.5:1 isn't really a problem, even untuned, as my friend's car shows. If you can only get 92 or 91, you won't be able to go as high, maybe 12:1 or so. I'm sure there's plenty of examples to the contrary, these are just trends you'll see.

 

You can run any octane on any compression. Import builders used to have 13:1 compression engines that would run on 91 octane, but only @ part throttle and never uphill. 11.7:1 is what i have found to be safe with a really good tune on 91 octane.

Also, with shorter rods and big cams you can run more compression.

 

yeah... i'm in oregon so premium is 92 and according to the calculator i will be at a little over 12.:1 so i guess i'll be alright thanks guys.